1. Field of the Invention
The present invention relates to a bacteriophage isolated from the nature that infects and kills Pasteurella multocida cells, and a method for preventing and treating the infections of Pasteurella multocida using a composition comprising the bacteriophage as an active ingredient. More particularly, the present invention relates to a Myoviridae bacteriophage Pas-MUP-1 (Accession NO: KCTC 12706BP) that is isolated from the nature and can kill Pasteurella multocida cells specifically, which has a genome represented by the nucleotide sequence of SEQ. ID. NO: 1, and a method for preventing the infections of Pasteurella multocida and thereafter treating them using the composition comprising said bacteriophage as an active ingredient.
2. Description of the Related Art
Pasteurella multocida is a Gram-negative, non-motile bacillus, which is classified according to capsular polysaccharides into 5 types: A, B, D, E and F. In detail, Pasteurella multocida type A is associated with pulmonary diseases in cattle, sheep, pigs, Pasteurella multocida type B provokes hemorrhagic sepsis in cattle and buffalo, and Pasteurella multocida type D triggers atrophic rhinitis in pigs. As such, Pasteurella multocida gives rise to various diseases in livestock animals, thus leading to economical damages seriously in the livestock farming industry. Therefore, it is required to develop a novel procedure for preventing diseases and conditions caused by Pasteurella multocida in animals, and further treating the infections of Pasteurella multocida. 
In the livestock farming industry, antibiotics are utilized a lot in order to prevent and treat the infections of Pasteurella multocida. However, antibiotic-resistant bacterial strains are emerging so as to continuously reduce the effectiveness of antibiotics. Moreover, such an abuse of antibiotics for animals is being prohibited under national regulations fortified. Therefore, it is currently requested to develop a novel effective procedure rather than antibiotics. Especially, environmental-friendly methods may be preferred.
Recently, the use of bacteriophages has drawn our attention as a new way of treating bacterial infections. Particularly, the reason of our high interest in bacteriophages is because bacteriophage-based treatment is a nature-friendly method. Bacteriophages are an extremely small microorganism that infects bacteria, which are called phage in short. Once bacteriophage infects bacteria, the bacteriophage is proliferated in the inside of the bacterial cell. After proliferation, the progenies destroy the bacterial cell wall to escape from the host, suggesting that the bacteriophage has the killing ability of bacteria. The bacteriophage infection is characterized by its high specificity, so that a certain bacteriophage infects only a specific bacterium. That is, the bacterium that can be infected by certain bacteriophage is limited, suggesting that bacteriophage can kill only a specific bacterium and cannot harm other bacteria. Due to this cell specificity, the bacteriophage confers antibacterial effects upon target bacteria and excludes commensal bacteria in environmental or internal conditions of animal. Conventionally, universal antibiotics for therapeutic use of bacteria affect various kinds of bacteria coincidently, which results in a lot of problems polluting environment, disturbing normal microflora in animals or the like. Fortunately, the use of bacteriophages does not affect normal microflora and the like, because of killing the target bacteria selectively. Hence, the bacteriophage may be safe and thus lessen the probability of adverse actions, compared to any other antibiotics.
Bacteriophage was first found out by an English bacteriologist Twort in 1915 when he noticed that Micrococcus colonies melted and became transparent by something unknown. In 1917, a French bacteriologist d'Herelle found out that Shigella dysenteriae in the filtrate of dysentery patient feces melted by something, and further studied about this phenomenon. As a result, he identified bacteriophage independently, and named it as bacteriophage which means a bacteria killer. Since then, bacteriophages specifically acting against such pathogenic bacteria as Shigella, Salmonella Typhi and Vibrio cholerae have been continuously identified.
Owing to the unique capability of bacteriophage to kill bacteria, bacteriophages have been studied and anticipated as a better method to treat bacterial infections. However, after penicillin was found by Fleming, studies on bacteriophages had been only continued in some of Eastern European countries and the former Soviet Union because of the universalization of antibiotics. After the year of 2000, the merit of the conventional antibiotics faded because of the increase of antibiotic-resistant bacteria. So, bacteriophages are once again spotlighted as a new antibacterial agent that can replace the conventional antibiotics. Furthermore, the recent regulation of using antibiotics is fortified by the government world-widely. The interest on bacteriophages is increasing more and also industrial applications are increasingly achieved.
As demonstrated above, bacteriophages tend to be highly specific for bacteria. The specificity often makes bacteriophages effective upon a part of bacteria, even though belonging to the same kinds. In addition, the effectiveness of bacteriophage is different, depending upon target bacterial strains. Therefore, it is necessary to collect many kinds of bacteriophages that are useful to control specified bacteria efficiently. Hence, in order to develop a use of bacteriophages for coping with Pasteurella multocida, a lot of bacteriophages (many kinds of bacteriophages that give an antibacterial action against Pasteurella multocida) should be acquired. Furthermore, the resulting bacteriophages need to be screened whether or not superior to others in respects of antibacterial strength and spectrum.
Therefore, the present inventors tried to develop a composition applicable for the prevention or treatment of Pasteurella multocida infections by using a bacteriophage that is isolated from the nature and can kill Pasteurella multocida cells selectively, and further to establish a method for preventing or treating the infections of Pasteurella multocida using the composition. As a result, the present inventors isolated bacteriophages suitable for this purpose and secured the nucleotide sequence of the genome that distinguishes the bacteriophage of the present invention from other bacteriophages. Then, we have developed a composition comprising the isolated bacteriophage as an active ingredient, and confirmed that this composition could be efficiently used to prevent and treat the infections of Pasteurella multocida, leading to the completion of the present invention.